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List: linux-stable-commits
Subject: patch net-sock_copy-fixes.patch added to 2.6.30-stable tree
From: <gregkh () suse ! de>
Date: 2009-07-29 14:50:59
Message-ID: 20090729145203.29E9649110 () coco ! kroah ! org
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This is a note to let you know that we have just queued up the patch titled
Subject: net: sock_copy() fixes
to the 2.6.30-stable tree. Its filename is
net-sock_copy-fixes.patch
A git repo of this tree can be found at
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
From 89b8dcb97369f49e1d44535d34a797457325018a Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 28 Jul 2009 18:59:07 -0700
Subject: net: sock_copy() fixes
From: Eric Dumazet <eric.dumazet@gmail.com>
[ Upstream commit 4dc6dc7162c08b9965163c9ab3f9375d4adff2c7 ]
Commit e912b1142be8f1e2c71c71001dc992c6e5eb2ec1
(net: sk_prot_alloc() should not blindly overwrite memory)
took care of not zeroing whole new socket at allocation time.
sock_copy() is another spot where we should be very careful.
We should not set refcnt to a non null value, until
we are sure other fields are correctly setup, or
a lockless reader could catch this socket by mistake,
while not fully (re)initialized.
This patch puts sk_node & sk_refcnt to the very beginning
of struct sock to ease sock_copy() & sk_prot_alloc() job.
We add appropriate smp_wmb() before sk_refcnt initializations
to match our RCU requirements (changes to sock keys should
be committed to memory before sk_refcnt setting)
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
include/net/sock.h | 32 +++++++++++++++++++-------------
net/core/sock.c | 20 ++++++++++++++++++--
2 files changed, 37 insertions(+), 15 deletions(-)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -103,15 +103,15 @@ struct net;
/**
* struct sock_common - minimal network layer representation of sockets
+ * @skc_node: main hash linkage for various protocol lookup tables
+ * @skc_nulls_node: main hash linkage for UDP/UDP-Lite protocol
+ * @skc_refcnt: reference count
+ * @skc_hash: hash value used with various protocol lookup tables
* @skc_family: network address family
* @skc_state: Connection state
* @skc_reuse: %SO_REUSEADDR setting
* @skc_bound_dev_if: bound device index if != 0
- * @skc_node: main hash linkage for various protocol lookup tables
- * @skc_nulls_node: main hash linkage for UDP/UDP-Lite protocol
* @skc_bind_node: bind hash linkage for various protocol lookup tables
- * @skc_refcnt: reference count
- * @skc_hash: hash value used with various protocol lookup tables
* @skc_prot: protocol handlers inside a network family
* @skc_net: reference to the network namespace of this socket
*
@@ -119,17 +119,21 @@ struct net;
* for struct sock and struct inet_timewait_sock.
*/
struct sock_common {
- unsigned short skc_family;
- volatile unsigned char skc_state;
- unsigned char skc_reuse;
- int skc_bound_dev_if;
+ /*
+ * first fields are not copied in sock_copy()
+ */
union {
struct hlist_node skc_node;
struct hlist_nulls_node skc_nulls_node;
};
- struct hlist_node skc_bind_node;
atomic_t skc_refcnt;
+
unsigned int skc_hash;
+ unsigned short skc_family;
+ volatile unsigned char skc_state;
+ unsigned char skc_reuse;
+ int skc_bound_dev_if;
+ struct hlist_node skc_bind_node;
struct proto *skc_prot;
#ifdef CONFIG_NET_NS
struct net *skc_net;
@@ -207,15 +211,17 @@ struct sock {
* don't add nothing before this first member (__sk_common) --acme
*/
struct sock_common __sk_common;
+#define sk_node __sk_common.skc_node
+#define sk_nulls_node __sk_common.skc_nulls_node
+#define sk_refcnt __sk_common.skc_refcnt
+
+#define sk_copy_start __sk_common.skc_hash
+#define sk_hash __sk_common.skc_hash
#define sk_family __sk_common.skc_family
#define sk_state __sk_common.skc_state
#define sk_reuse __sk_common.skc_reuse
#define sk_bound_dev_if __sk_common.skc_bound_dev_if
-#define sk_node __sk_common.skc_node
-#define sk_nulls_node __sk_common.skc_nulls_node
#define sk_bind_node __sk_common.skc_bind_node
-#define sk_refcnt __sk_common.skc_refcnt
-#define sk_hash __sk_common.skc_hash
#define sk_prot __sk_common.skc_prot
#define sk_net __sk_common.skc_net
unsigned char sk_shutdown : 2,
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -915,13 +915,19 @@ static inline void sock_lock_init(struct
af_family_keys + sk->sk_family);
}
+/*
+ * Copy all fields from osk to nsk but nsk->sk_refcnt must not change yet,
+ * even temporarly, because of RCU lookups. sk_node should also be left as is.
+ */
static void sock_copy(struct sock *nsk, const struct sock *osk)
{
#ifdef CONFIG_SECURITY_NETWORK
void *sptr = nsk->sk_security;
#endif
-
- memcpy(nsk, osk, osk->sk_prot->obj_size);
+ BUILD_BUG_ON(offsetof(struct sock, sk_copy_start) !=
+ sizeof(osk->sk_node) + sizeof(osk->sk_refcnt));
+ memcpy(&nsk->sk_copy_start, &osk->sk_copy_start,
+ osk->sk_prot->obj_size - offsetof(struct sock, sk_copy_start));
#ifdef CONFIG_SECURITY_NETWORK
nsk->sk_security = sptr;
security_sk_clone(osk, nsk);
@@ -1118,6 +1124,11 @@ struct sock *sk_clone(const struct sock
newsk->sk_err = 0;
newsk->sk_priority = 0;
+ /*
+ * Before updating sk_refcnt, we must commit prior changes to memory
+ * (Documentation/RCU/rculist_nulls.txt for details)
+ */
+ smp_wmb();
atomic_set(&newsk->sk_refcnt, 2);
/*
@@ -1809,6 +1820,11 @@ void sock_init_data(struct socket *sock,
sk->sk_stamp = ktime_set(-1L, 0);
+ /*
+ * Before updating sk_refcnt, we must commit prior changes to memory
+ * (Documentation/RCU/rculist_nulls.txt for details)
+ */
+ smp_wmb();
atomic_set(&sk->sk_refcnt, 1);
atomic_set(&sk->sk_drops, 0);
}
Patches currently in stable-queue which might be from eric.dumazet@gmail.com are
queue-2.6.30/net-sk_prot_alloc-should-not-blindly-overwrite-memory.patch
queue-2.6.30/net-sock_copy-fixes.patch
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